Frequency of the VNTR-Polymorphisms at the PAH Gene in the Iranian Azeri Turkish Patients with Phenylketonuria

This study was carried out to determine the frequency of the VNTR-polymorphisms at
the PAH gene in the Iranian Azeri Turkish patients with phenylketonuria (PKU) and normal controls.
Material and methods: The VNTR-polymorphisms were determined by PCR in 43 PKU patients
as well as 43 controls.
Outcomes: The frequencies of VNTR-alleles were 13(15.1%), 3(3.49%), 64(74.4%), 5(5.81%), and
1(1.16%) in the patients and 43(50%), 0(0%), 42(48.8%), 0(0%), and 1(1.16%) in the controls regarding 3, 7, 8, 9, and 11 repeat copies, respectively. The VNTR alleles with 12 and 13 repeats were not found
in our samples. The frequencies of VNTR-genotypes were 25(58.1%), 1(2.33%), 1(2.33%), 10(23.3%),
2(4.65%), 2(4.65%), 1(2.33%), 1(2.33%), and 0(0%) in the patients and 13(30.2%), 13(30.2%), 0(0%),
16(37.2%), 0(0%), 0(0%), 0(0%), 0(0%) and 1(2.33%) in the controls regarding VNTR8/VNTR8,
VNTR3/VNTR3, VNTR3/VNTR9, VNTR8/VNTR3, VNTR8/VNTR9, VNTR7/VNTR9, VNTR7/
VNTR8, VNTR8/VNTR11, and VNTR3/VNTR11 genotypes, respectively. The comparisons of VNTRpolymorphisms imply that there are statistically significant differences between the patients and controls regarding VNTR3, VNTR8, and VNTR9 alleles as well as VNTR8/VNTR8 and VNTR3/VNTR3
genotypes (all P-Value <0.05). The frequency of “risk-associated genotype of VNTR8/VNTR8” was
significantly higher in the cases.
Conclusions: It is concluded that this position is heterozygous and there were statistically significant
differences between patients and controls concerning the VNTR8/VNTR8 genotype. We found higher
frequencies of disease-associated genotype in our samples than controls. This report is the first in its own
type in the west Azerbaijani population. Further studies require assessing how this genotype predicts
adverse outcomes in tested population.